OBJECTIVE To investigate the mechanism of pachymic acid on renal injury in pregnancy induced hypertension （PIH） rats by regulating the silent information regulator transcript 1/peroxisome proliferator-activated receptor γ coactivator-1α （Sirt1/PGC-1α） pathway. METHODS Pregnant SD rats were prepared by co-caging and PIH model was induced using N-nitro-L- arginine methyl ester （L-NAME） method. PIH rats were randomly divided into model group， L-pachymic acid （low-dose pachymic acid， 10 mg/kg） group， H-pachymic acid （high-dose pachymic acid， 20 mg/kg） group， and H-pachymic acid+EX527 （20 mg/kg pachymic acid+10 mg/kg EX527） group， with 6 rats in each group. Another 6 normal pregnant rats were selected as blank group. Each group was given relevant medicine or solvent intragastrically or intraperitoneally daily， once a day， for 28 consecutive days. After the last administration， 24 h urinary protein and tail artery systolic blood pressure （SBP） were measured in pregnant rats from each group， along with the levels of serum creatinine （Scr）， blood urea nitrogen （BUN），uric acid （UA）， and cystatin C （Cys-C）. The contents of superoxide dismutase （SOD）， malondialdehyde （MDA）， glutathione peroxidase （GSH-Px）， and 8-hydroxy-2′-deoxyguanosine （8-OHdG） in renal tissue， as well as the mRNA and protein expression levels of Sirt1 and PGC-1α， were also determined. Meanwhile， renal histopathological changes in rats from each group were evaluated using hematoxylin-eosin （HE） staining and periodic acid-Schiff （PAS） staining. RESULTS Compared with model group， L-pachymic acid group and H-pachymic acid group exhibited significant decreases in 24 h urine protein quantification， tail artery SBP， Scr， BUN， UA， Cys-C levels， glomerulosclerosis index score of renal tissue， renal tubular injury score， the percentage of PAS positive area， MDA and 8-OHdG （P＜0.05）. Conversely， the contents of SOD and GSH-Px， along with the mRNA and protein expression levels of Sirt1 and PGC-1α， were significantly increased （P＜0.05）. Moreover， these improvements were more pronounced in H-pachymic acid group （P＜0.05）. Compared with H-pachymic acid group， the aforementioned indicators in pregnant rats from the H-pachymic acid+EX527 group showed significant reversal （P＜0.05）. CONCLUSIONS Pachymic acid significantly ameliorates renal injury induced by PIH in rats， potentially through activation of the Sirt1/PGC-1α pathway.

ObjectiveThe exacerbating trend of global population aging poses profound socioeconomic and public health challenges, making the comprehensive elucidation of biological aging mechanisms and the discovery of effective anti-aging interventions an urgent priority in the life sciences. Based on our previous serum metabolomics findings that dimethylglycine, an intermediate metabolite of amino acid metabolism naturally present in the human body, was significantly enriched in the serum of longevity families, this study aimed to systematically investigate the anti-aging effects of dimethylglycine both in living organisms and in controlled laboratory environments, and to preliminarily elucidate its underlying molecular mechanisms. While existing literature indicates that dimethylglycine possesses antioxidant and immunomodulatory properties, its direct anti-aging efficacy and the specific molecular pathways through which it operates remain largely unexplored. MethodsTo comprehensively evaluate the anti-aging properties of dimethylglycine, we utilized replicative senescent human embryonic lung fibroblasts, specifically the WI-38 cell line, as an experimental model in a controlled laboratory environment. Cell viability and safety were thoroughly assessed using Cell Counting Kit-8 and lactate dehydrogenase release assays across various concentrations of dimethylglycine. The impact of dimethylglycine on cellular senescence phenotypes, oxidative stress, and proliferative capacity was evaluated via senescence-associated beta-galactosidase staining, reactive oxygen species fluorescence detection, and 5-ethynyl-2'-deoxyuridine incorporation assays. Furthermore, the molecular alterations of senescence-associated secretory phenotype factors and core senescence signaling pathways were quantified using quantitative reverse transcription polymerase chain reaction for the messenger RNA levels of interleukin-6, interleukin-8, p21, and matrix metalloproteinase-1, and enzyme-linked immunosorbent assay for the measurement of p16 and p21 protein expression levels. For the living organism model, the wild-type nematode Caenorhabditis elegans was used to evaluate systemic physiological effects. We conducted a comprehensive lifespan analysis at 20°C, heat stress resistance survival assays at 35℃, senescence-associated beta-galactosidase staining, lipofuscin accumulation tracking, intracellular reactive oxygen species measurement, and Oil Red O staining to ascertain systemic lipid accumulation. Additionally, network pharmacology bioinformatics tools, including PharmMapper and STRING databases, and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis were utilized to predict target pathways, alongside highly detailed molecular docking simulations utilizing SwissDock and Protein-Ligand Interaction Profiler to examine interactions with the cytochrome P450 family 2 subfamily C member 9 protein. ResultsThe experimental outcomes robustly demonstrate the potent anti-aging capabilities of dimethylglycine. At the cellular level, toxicity analyses firmly confirmed that dimethylglycine is highly safe; continuous treatment with 50 mol/L and 70 mol/L of dimethylglycine for 5 d did not induce any cellular membrane damage or cytotoxicity, but rather actively promoted cellular proliferation. Utilizing the optimal standardized concentration of 50 mol/L, dimethylglycine treatment significantly ameliorated senescent phenotypic markers in human embryonic lung fibroblasts, which was evidenced by a drastic and highly significant reduction in the senescence-associated beta-galactosidase positive cell percentage (P<0.000 1) and intracellular reactive oxygen species levels (P<0.000 1), alongside a marked increase in the 5-ethynyl-2'-deoxyuridine-positive proliferation rate (P=0.003 5). On a molecular expression scale, dimethylglycine significantly downregulated the messenger RNA expression of multiple core senescence-associated secretory phenotype inflammatory factors, including interleukin-6, interleukin-8, p21, and matrix metalloproteinase-1. Concurrently, it effectively suppressed the protein expression of critical cell cycle arrest markers, diminishing p16 protein levels by 57.3% (P=0.000 4) and p21 protein levels by 27.2% (P=0.000 7). In the nematode Caenorhabditis elegans animal model, dimethylglycine significantly extended the mean lifespan from 20.402 d to an impressive 23.066 d (P<0.000 1) and notably enhanced overall survival rates under severe heat stress environmental conditions (P=0.017). Furthermore, systemic dimethylglycine intervention significantly mitigated age-related physiological decline by decreasing bodily lipofuscin accumulation (P<0.000 1), significantly reducing senescence-associated beta-galactosidase activity, lowering systemic reactive oxygen species fluorescence (P=0.008), and effectively alleviating overall fat accumulation (P<0.000 1). Mechanistically, extensive network pharmacology and Kyoto Encyclopedia of Genes and Genomes analyses strongly revealed that the potential targets of dimethylglycine are significantly enriched in fundamental drug metabolism and oxidative stress response pathways. Precision molecular docking simulations conclusively demonstrated that dimethylglycine forms highly stable structural interactions with the cytochrome P450 family 2 subfamily C member 9 protein, specifically highlighting the definitive formation of 5 stable hydrogen bonds involving serine 365, leucine 366, and serine 429 residues, as well as two critical salt bridge formations with arginine 97 and histidine 368 residues. It is additionally predicted to interact favorably with glutathione S-transferase family proteins. ConclusionDimethylglycine exhibits a profoundly significant and multifaceted anti-aging activity at both the cellular and entire living animal levels. By powerfully alleviating oxidative stress, heavily suppressing the core p16 and p21-dependent cellular senescence signaling pathways, and substantially mitigating the detrimental senescence-associated secretory phenotype, dimethylglycine effectively delays fundamental cellular senescence processes and drastically extends whole-organism lifespan. The biological mechanisms driving these robust protective effects are highly likely closely associated with its direct stable interactions with crucial metabolic and detoxifying enzyme systems, such as cytochrome P450 family 2 subfamily C member 9 and glutathione S-transferase family proteins, thereby systemically improving metabolic dysregulation and restoring critical redox homeostasis. This comprehensive study provides highly solid experimental evidence supporting dimethylglycine as a highly potent and safe potential anti-aging intervention agent, while simultaneously offering a clear molecular mechanistic explanation for the previously documented high abundance of dimethylglycine observed within exceptionally long-lived human populations.

ObjectiveTo explore the effect of oral sodium butyrate on skeletal muscle atrophy in CT26 tumor mice through the gut microbiota-skeletal muscle axis and its potential mechanism. MethodsSixty SPF BALB/c male mice aged 8 weeks were randomly divided into a normal control group (NC, n=18) and a ABX-depleted group (ABX, n=42). The ABX mice were pretreated with a quadruple antibiotic cocktail via oral gavage (0.2 ml per administration, once daily, 6 d per week, for 2 weeks), whereas NC received an equal volume of sterile water. The quadruple antibiotic cocktail consisted of metronidazole (1 g/L), vancomycin (0.5 g/L), ampicillin (1 g/L), and gentamicin (1 g/L). Following successful pretreatment, six mice from each group were randomly selected for gut microbiota sequencing analysis and designated as the Abx group and the NC0 group, respectively. Theremaining mice in ABX were subcutaneously inoculated in the dorsum with 0.2 ml of CT26 cell suspension (at a cell density of 1×10⁷/ml). Then these mice were randomly allocated into three subgroups: a control tumor bearing model group (0_NaB, n=12), a tumor-bearing model group receiving low-dose oral sodium butyrate (L_NaB, n=12), a tumor-bearing model group receiving high-dose oral sodium butyrate (H_NaB, n=12). And mice in NC were inoculated at the same site with 0.2 ml of normal saline. The administration dose for L_NaB was 0.3 g/(kg·d), that for H_NaB was 0.5 g/(kg·d), while NC and 0_NaB were given the same volume of normal saline (0.2ml per time, once daily, 6 d per week, for 4 weeks). The general condition of mice was monitored, and forelimb grip strength gastrocnemius muscle mass and its muscle fiber cross-sectional area were measured for each group. The structural changes in gut microbiota were assessed by 16S rRNA sequencing of cecal contents. Pathological alterations in the intestinal wall were examined via HE staining. Serum and gastrocnemius muscle levels of TNF‑α, IL-6, IL-1β, and LPS were quantified using ELISA. The protein expression of ZO-1 and occludin in the small intestine, as well as proteins associated with the TLR4/MyD88/NF-κB signaling pathway in the gastrocnemius muscle, were detected by Western blot analysis. Results(1) The alpha-diversity in Abx was significantly lower than that in NC0 (P<0.01), a significant decrease of the mass and muscle fiber cross-sectional area of the gastrocnemius (P<0.01), with the majority of gut microbiota being effectively depleted. (2) Compared with NC, the subcutaneous tumors of mice in 0_NaB were prominent, a significant increase of the mass and muscle fiber cross-sectional area of the gastrocnemius, accompanied by a significant decrease in body weight at the end of the 3th and 4th week (P<0.05), and a significant weakening of the forelimb grasping strength at the 5th and 6th week (P<0.01). Compared with 0_NaB, the tumor mass of mice in L_NaB and H_NaB showed a significant decreasing trend, and the grip strength of the forelimbs significantly increased at the 5th and 6th week (P<0.05, P<0.01). (3) Compared with 0_NaB, the Shannon and Observed species indices in α diversity of L_NaB and H_NaB were significantly increased (P<0.05). At the genus level, compared with 0_NaB, L_NaB exhibited a significant decrease in the relative abundance of Parasutterella (P< 0.01), while H_NaB showed significant reductions in the relative abundances of both Escherichia-Shigella and Parasutterella (P < 0.01). (4) Compared with 0_NaB, the small intestinal tissue structure in L_NaB and H_NaB was more intact, the infiltration of inflammatory cells was significantly reduced, and the capillaries were slightly dilated. The expression levels of ZO-1 and occludin proteins in L_NaB were significantly increased (P<0.01). (5) The LPS concentration in the gastrocnemius muscle and the protein expression levels of TLR4, MyD88, p-IκBα, and p-NF‑κB p65 in L_NaB and H_NaB were significantly lower than those in 0_NaB (P<0.05). The serum TNF‑α concentration in H_NaB and TNF-α concentration in the gastrocnemius muscle of the L_NaB and H_NaB were significantly lower than those in 0_NaB (P<0.05, P<0.01, P<0.01). ConclusionOral administration of NaB can improve gut microbiota α diversity, adjusting its composition, improving intestinal mucosal barrier function, reducing the LPS-induced pro-inflammatory response, and delaying skeletal muscle atrophy. The underlying mechanism may involve down regulation of TLR4/MyD88/NF-κB signaling in skeletal muscle.

ObjectiveHepatocellular carcinoma (HCC) represents 90% of all primary liver cancers. The main risk factors associated with HCC include viral hepatitis (B and/or C), alcohol abuse, and metabolic dysfunction-associated steatotic liver disease (MASLD), which progressively advance to liver fibrosis, cirrhosis, and ultimately evolve into HCC. Surgical resection represents the most effective treatment for HCC, while recent advances in immunotherapy, including immune checkpoint inhibitors and adoptive cell therapies, have provided improved treatment prospects for patients with unresectable HCC. However, the complex metabolic heterogeneity of HCC limits the therapeutic efficacy. Metabolic intermediates acyl-CoA not only provide energy and substrates for numerous biochemical reactions but also serve as donors for protein lysine acylation, a major class of post-translational modification (PTM). Therefore, a deeper understanding of the molecular mechanisms underlying protein lysine acylation and hepatocarcinogenesis is urgently needed. MethodsThe levels of protein lysine acylation and silence information regulator 5 (SIRT5) expression levels in clinical HCC samples were analyzed by Western blot. Quantitative malonylome and succinylome of HCC samples were analyzed by antibody-based affinity enrichment coupled with tandem mass spectrometry. The proliferation of HCC cells was analyzed with Cell Counting Kit-8 (CCK-8) assays, the apoptosis was quantified by Annexin V-FITC/propidium iodide (PI) staining coupled with flow cytometry, and the ability of cells to migrate was assayed by Transwell assays. The enzymatic activity of glutathione S-transferase Mu 1 (GSTM1) was quantified. Transgenic mice with hepatic overexpression of SIRT5 were constructed using CRISPR-Cas9, and primary hepatocarcinogenesis was induced by administration of diethylnitrosamine. ResultsWestern blot analysis indicated that the expression level of SIRT5 was elevated in clinical samples from HCC patients, and the levels of lysine malonylation, glutarylation, and succinylation were significantly reduced in HCC tissues. Knockout of SIRT5 in MHCC-97H and MHCC-97L hepatoma cells suppressed cell proliferation, and increased the percentage of apoptotic cells significantly. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses of the differentially malonylome and succinylome of HCC samples revealed significant enrichment in two major classes of biological processes: core energy metabolism (e.g., glycolysis/gluconeogenesis, tricarboxylic acid metabolic process, fatty acid beta oxidation) and detoxification and oxidative stress response (e.g., response to toxic substance, chemical carcinogenesis, reactive oxygen species (ROS)). SIRT5 removes malonylation from lysine residues in GSTM1 and restores its detoxification activity, which is crucial for the survival of hepatocytes under stressed conditions. More importantly, in vivo experiment indicated that hepatic-specific overexpression of SIRT5 in mice accelerated diethylnitrosamine-induced liver fibrosis and hepatocarcinogenesis, indicating the critical role of SIRT5 in HCC progression. ConclusionThis study highlights the previously unrecognized SIRT5-GSTM1 axis as a key regulator in hepatocarcinogenesis, and suggests a potential target for the treatment of patients with HCC.

Background: and Purpose Vertebrobasilar fusiform aneurysms (VBFAs) carry substantial morbidity and mortality, but optimal management for unruptured VBFAs remains unclear. We compared the safety and efficacy of conservative management (CM), stent-assisted coiling (SAC), and flow diverters (FDs) in patients with unruptured VBFAs, focusing on long-term prognosis. Methods: This study included data from a nationwide Chinese cohort of patients with vertebrobasilar dissecting aneurysms. Inverse probability of treatment weighting (IPTW) balanced confounders across groups. The primary outcome was poor prognosis (modified Rankin Scale score >2). Secondary outcomes included aneurysm rupture, ischemic stroke, compression symptoms, and VBFA-related deaths. Logistic regression estimated odds ratios (ORs) and 95% confidence intervals (CIs). Subgroup and sensitivity analyses were performed. Results: Among 1,115 patients with unruptured VBFAs, 838 (median age, 54 years; 655 men) were included. After IPTW, baseline characteristics were balanced. Median follow-up was 54 months. FD was associated with a lower risk of poor prognosis than CM (OR, 0.48 [95% CI, 0.30 to 0.77]; p=0.002), with no difference between CM and SAC. FD also reduced aneurysm rupture (OR, 0.20 [95% CI, 0.07 to 0.60]; p=0.004) and compression symptoms (OR, 0.30 [95% CI, 0.13 to 0.68]; p=0.004) versus CM. Time-to-event analyses further revealed significant differences in vertebral artery lesions and Type I–II VBFAs, whereas no significant differences were observed in basilar or vertebrobasilar junction lesions or in Type III–IV VBFAs. Conclusions Compared with CM, FD was associated with improved long-term outcomes in unruptured VBFAs, particularly in vertebral artery lesions and Type I–II VBFAs, although residual confounding cannot be excluded.

Objective: To explore the association between executive function and emotional and behavioral problems in first-grade elementary school students, so as to provide a reference for promoting children s mental health. Methods: From March to May 2024, 423 first-grade elementary school students from 6 primary schools aged 6-7 were selected by using stratified cluster random sampling in Shanxi, Shanghai, Shandong, Guangxi, Xinjiang, and Jiangxi. Data were collected by using the Executive Function Assessment Scale and the Strengths and Difficulties Questionnaire. An independent samples t-test was used to analyze differences in executive function of different genders and differences in emotional and behavioral problems among first-grade school students with varying executive function levels; a linear regression model was employed to analyze the association between children s executive function and emotional and behavioral problems. Results: A total of 42 first-grade elementary school students (9.9%) were identified as having executive function deficits. Students in the executive function deficit group scored higher on internalizing behavior (7.50±0.52), externalizing behavior (11.26±0.52), and total difficulties (18.52± 0.93 ) were significantly higher than those of children without deficits (4.37±0.14, 6.69±0.17, 10.64±0.27) ( t =5.79, 8.50, 9.23, all P <0.05). Results of linear regression analysis showed that, after controlling for relevant covariates such as gender, age, family economic status, being an only child, and body mass index, the factor scores, dimensional scores, and total scores of executive function were all positively correlated with scores for externalizing problems, internalizing problems, and total difficulties ( β =0.07-0.32, all P <0.05). Conclusions Children s executive function is closely associated with emotional and behavioral problems, and those with poorer executive function exhibit more pronounced emotional and behavioral problems. Improving children s executive function may help promote their mental health.

Red doctor spirit， as an important component of the Chinese revolutionary culture， represents a valuable spiritual wealth formed by the Communist Party of China during the revolutionary and construction periods. Red doctor spirit shares the same spiritual core， consistent moral pursuits， and unified value orientations with medical ethics education for medical students. Integrating red doctor spirit into medical ethics education for medical students contributes to strengthening their political beliefs， enhancing their professional competence， shaping their professional ethics， and cultivating their practical literacy. Medical colleges and universities should employ paths such as integrating red doctor spirit into classroom teaching， inheriting it through practical process， promoting it in cultural construction， and nurturing it through diverse carriers. These aim to cultivate medical students’ unwavering political beliefs， trustworthy medical skills， selfless moral convictions， and professional confidence in healing the sick， therefore guiding medical students to become high-quality medical talents with noble medical ethics and superb medical skills.

Abstract The cooccurrence of multi disease among children and adolescents has become increasingly prominent, necessitating a shift from "single disease separate treatment" to "multi disease co prevention". Focusing on four common health problems in children and adolescents, namely, myopia, depression, overweight/obesity, and spinal abnormalities, the paper systematically reviews the association between four categories of factors, society, environment, family, and individual behavior, and the co occurrence of the aforementioned health problems. The findings indicate that particulate matter 2.5 exposure, light at night, physical inactivity, excessive screen time, and unhealthy diet constitute the primary cross dimensional risk network. Based on these findings, the paper proposes a collaborative action framework involving family, school, and society, emphasizing systematic strategies ranging from upstream environmental governance to downstream behavioral intervention, so as to provide evidence for the practice and policy making of multi disease co-prevention in children and adolescents.

OBJECTIVE To evaluate the quality of Zhachong-13 pills.METHODS The contents of agarotetrol， costunolide， hypaconitine， dehydrocostus lactone， mesaconitine， aconitine， liquiritigenin， glycyrrhizic acid， ellagic acid， liquiritin， corilagin， and gallic acid in 18 batches of samples were determined by high-performance liquid chromatography-tandem triple quadrupole mass spectrometry （HPLC-MS/MS） method. Cluster analysis （CA） was performed using the Microbioinformatics online analysis platform. Principal component analysis （PCA） and orthogonal partial least squares discriminant analysis （OPLS-DA） were performed using SIMCA 14.1 software. Random forest， extremely randomized trees， and extreme gradient boosting machine learning models were constructed using the SPSSAU online analysis platform. The comprehensive quality of the samples was evaluated by the entropy weight-technique for order preference by similarity to ideal solution （TOPSIS） method.RESULTS The contents of the above 12 components were 104.331-694.382， 652.217-1 085.075， 6.051-130.980， 612.174-1 417.179， 1.018-32.239， 0.953-24.967， 65.552-652.239， 2 019.412-5 385.807， 52.867-4 990.450， 156.307-883.180， 10.142-475.722， and 1 102.863-4 826.396 μg/g， respectively. The results of CA and PCA showed that the 18 batches of samples were divided into two categories： S1-S6， S10-S15 were grouped into one category， while S7-S9 and S16-S18 were grouped into another category. The OPLS-DA results showed that the variable importance in projection values of mesaconitine， glycyrrhizic acid， liquiritin， ellagic acid， hypaconitine， liquiritigenin， agarotetrol， gallic acid， and dehydrocostus lactone were greater than 1. The results of the three machine learning models showed that ellagic acid and hypaconitine had relatively large differential contributions. The entropy weight-TOPSIS results showed that the overall quality of samples from manufacturer B was superior to that of the other four manufacturers.CONCLUSIONS The established method is stable and feasible， and can be used to evaluate the quality of Zhachong-13 pills， in combination with multivariate statistical analysis. Ellagic acid and hypaconitine are differential markers that affect its quality.

Objective: To explore the association between mental health and muscle strength among Chinese adolescents aged 13- 18, providing a theoretical foundation and intervention strategies for mental health promotion. Methods: Data were obtained from the 2019 Chinese National Survey on Students Constitution and Health, including 98 631 Chinese adolescents aged 13- 18. Psychological distress was assessed by using the Kessler Psychological Distress Scale (K10), and mental well being was measured with the Warwick-Edinburgh Mental Well being Scale (WEMWBS). Based on the gender and age specific Z scores of various test items [grip strength, standing long jump, pull ups (for males), and sit ups (for females)], muscle strength index (MSI) was constructed to evaluate the comprehensive level of muscle strength in adolescents. According to the Dual factor Model (DFM) of mental health, participants were categorized into four groups:troubled, symptomatic but content, vulnerable, and complete mental health. Gender differences were analyzed by using Chi-square tests, trends were tested with Cochran-Armitage tests, and multinomial Logistic regression models were applied to assess associations between muscle strength and mental health among adolescents. Results: In 2019, 37.4% of Chinese adolescents aged 13-18 were reported of high mental distress, and 59.9% were reported of low mental well being. Boys had significantly lower rates of high mental distress (35.3%) and low mental well being (55.6%) compared to girls (39.4%, 64.3%), and the differences were of statistical significance ( χ 2=176.13, 780.42, both P <0.05). In 2019, the rate of complete mental health among adolescents showed a downward trend with increasing age ( χ 2 trend = 258.47) and a gradual upward trend with increasing muscle strength levels ( χ 2 trend =123.14)，and both boys and girls exhibited similar trends ( χ 2 trend =103.83, 168.46; 57.00 , 67.34) (all P <0.05). The results of the unordered multiclass Logistic regression model showed that after controlling for confounding factors such as age and gender, when the completely pathological group as a reference, for every 1 unit increase in MSI in adolescents, the likelihood of being in a completely mental health state increased by 29% ( OR = 1.29); for every unit increase in the Z-score for pull ups, the likelihood of being in a completely mental health state increased by 6% ( OR =1.06) among boys; for every 1 unit increase in sit up Z score, the likelihood of being in a completely mental health state increased by 19% ( OR =1.19) among girls (all P <0.05). Conclusions The mental health status of Chinese adolescents is not good enough. Muscle strength is positively associated with mental health.